Jidosha Kiki Co., Ltd.

Other

Bosch Automotive Systems Corporation

Satoru Watanabe

Masahiro Shimada

Michio Kobayashi

Mamoru Sawada

Yuzo Imoto

Hidefumi Inoue

Hiroyuki Oka

Junichi Hirayama

Masaki Machida

In a negative pressure boosting device of the present invention, upon depression of a pedal at a normal speed, an input shaftand a valve plungermove forward to close a vacuum valveand open an atmospheric valveand a power pistona valve bodyand an output shaftmove forward. In the initial stage of operation, hooksandare not engaged with each other so that a cylindrical memberdoes not move forward, thereby shortening the stroke of the input shaftas compared to a conventional one. Upon rapid depression of the pedal, a press facepresses a pressed faceso as to deform an engaging arm portion, thereby disengaging the hooksandfrom each other. The cylindrical memberis moved backward by a springto push a vacuum valve portionso that the atmospheric valve portionis spaced apart from the atmospheric valve seatmore rapidly than that of the service braking, thereby increasing the jumping amount and thus rapidly intensifying the output.

Negative pressure boosting device

A fluid pressure boosting device of the present invention performs jumping action at a higher servo ratio until fluid pressure in a power chamber (,) reaches a first predetermined value and a rear end (,e) of a reaction piston (,)comes in contact with a step of an input shaft (,). Since a switching valve is set in a first position I until the fluid pressure in the power chamber (,) reaches a second predetermined pressure, a reaction chamber (,) is connected to the reservoir (,) so as to be at atmospheric pressure. In this state, the normal brake control at a lower servo ratio is performed. As the fluid pressure in the power chamber (,) reaches a second predetermined value, the switching valve is set in a second position II by the fluid pressure so that the pressurized fluid in the power chamber is introduced into the reaction chamber (,). The fluid pressure in the reaction chamber,acts on the step between the reaction piston (,) and the input shaft (,) so that the servo ratio becomes higher. Then, the servo control at a higher servo ratio is performed. The fluid pressure boosting device can be provided with the reversed two-stage servo characteristic, so with simple structure, output larger than the normal output can be obtained when input exceeds a predetermined value.

Fluid pressure boosting device and brake pressure boosting system employing the device

The collar 13 for slidably supporting and guiding a valve body of the control valve 55 of the hydraulic pressure type booster 1 is press-fitted into the small diameter portion 9a of the stepped hole 9 of the power piston 8. The valve seat member 10 of the control valve 55 is also press-fitted into the small diameter portion 9a. Further, the small diameter protrusion 6b of the stepped cylindrical protrusion 6a of the plug 6, which divides the power chamber 25, is also press-fitted into the small diameter portion 4a of the stepped hole 4 of the housing 3. In the cylindrical member 17 in which the second valve seat 17a of the control valve 55 is formed, the stopper 17b to restrict a limit of retraction of the input shaft 18 is integrally formed. Further, the cylindrical fixing member 11 to fix the flange 10a of the valve seat member 10 is fixed to the power piston 8 with C ring 12 in the axial direction.

Hydraulic pressure type booster

In a hydraulic boosting device of the present invention, when the pressure stored in an emergency accumulator is less than a set pressure, a stepped piston 70 moves downward, a throttle valve 72 is set in a first position where the throttle valve 72 is seated in a valve seat 71, and hydraulic fluid flowing from a pump through an inlet path 14 is restricted by a flow limiting valve 68 so as to develop a fluid pressure in an annular path 73. The fluid pressure is stored in the emergency accumulator through a path 69, an accumulator valve 27, and an accumulator path 31. When the pressure stored in the emergency accumulator exceeds the set pressure, the stepped piston 70 moves upward, the throttle valve 72 is set in a second position where the throttle valve 72 is apart from the valve seat 71, and the hydraulic fluid from the pump is not restricted by the flow limiting valve 68 at all so as to flow freely toward a control valve. In this state, no fluid pressure is developed in the annular path 73.

Hydraulic boosting device

A braking unit includes an intensifier mechanism for intensifying a braking liquid pressure of a master cylinder upon failure of a liquid pressure booster. The braking unit comprises the intensifier mechanism for intensifying the braking liquid pressure of the master cylinder when actuated, and a control valve which makes the intensifier mechanism operable upon failure of the liquid pressure booster. The control valve comprises a valve member which is urged by a spring tensioned with a given load and which is urged in the opposite direction from the spring by a liquid pressure of a power chamber of the liquid pressure booster. The valve member makes the intensifier mechanism operable whenever the resilience of the spring exceeds the urging force produced by the liquid pressure in the power chamber of the liquid pressure booster. This prevents an operational lag of the intensifier mechanism in the event the liquid pressure booster fails.

Growing community of inventors

Higashimatsuyama, Japan

Satoru Watanabe